The present invention relates to an outboard motor particularly having an improved air suction device such as aspirator therefor.
There is known an outboard motor including a multi-cylinder engine in which carburetors are continuously arranged in a vertical direction, as disclosed in Japanese Patent Laid-open Publication No. HEI 3-172570, for example.
Further, there is also known an outboard motor in which a fuel injector is disposed at a downstream portion of each manifold extending from a single throttle body, as disclosed in Japanese Patent Laid-open Publication No. HEI 6-16187, for example.
However, in the case of the suction device or intake device in which the carburetors are continuously arranged in a vertical direction, the structure becomes complicated, and positional layouts of the highest carburetor and the lowest carburetor are limited by a rotational surface of a flywheel and a lower cover section of an engine cover, respectively. As a result, the suction device is disposed so as to project outward from an engine, which prevents the engine from being reduced in size.
In the case of the suction device including the fuel injector, the idle revolution number of the engine is adjusted using a bypass air screw mounted to the throttle body. However, if the engine is to be reduced in size, the throttle body comes inside the engine and is surrounded by other parts, which makes it difficult to operate the bypass air screw is difficult.